Specimen changer for an x-ray fluorescence spectrometer



Dec. 10,1968 J. smms 3, 8

SPEVLMEN CHANGER FOR AN X-RAY FLUORESCENCE SPECTROMETER Filed Sept. -7, 1965 2 Sheets-Sheet 1 wveurap Jami wmrw J. SAHORES Dec. 10, 1968 SPECIMEN CHANGER FOR AN XRAY FLUORESCENCE SPECTROMETER 2 Sheets-Sheet 2 Filed Sept. 7, 1965 mvsmmz Jean Jakarta fimfiww ATTORNEYS United States Patent Office s 6 Claims. cl. 2s0 s1.s

ABSTRACT OF THE DISCLOSURE X-ray fluorescence spectrometer apparatus having a horizontal support plate with an analysis window, a cylindrical specimen holder magazine holding a plurality of specimen holders, and a rotary holder-transferring element having its axis of rotation at the center of the support plate. The transferring element automatically transferring, one at a time, the plurality of specimen holders from the holder to the analysis window where means for positioning and maintaining the specimen holder hold the specimen over the window during an analysis operation and then to a discharge recess formed in the support plate on the same path of rotation as the magazine and analysis window.

This invention relates to an X-ray fluorescence spectrometer.

In conventional X-ray spectrometer apparatus the specimens to be analysed are moved manually and the more sophisticated devices include a turret mechanism receiving four specimens. A standard must be used for every four specimens, so that three proper analyses are obtained by making four counts in a time of about 7 minutes. An operative must be permanently present for all these operations.

The present invention uses a system for automatically distributing specimen holders for X-ray fluorescence spectrometers, the object of the invention being to increase the number of analyses which can be made per unit of time and to obviate the need for permanent supervision by an operative, the system according to the invention using a distributor adapted to automatically remove a specimen at the completion of spectrometric analysis, to transfer a specimen for analysis from a specimen holder magazine to the spectrometer, to locate the specimen holder accurately relatively to the spectrometer and to rotate the specimen holder in its own plane and around its axis, for improved integration of the analysis over the whole surface of the specimen.

The invention is illustrated by way of example in the accompanying drawings, in which:

FIG. 1 shows an X-ray fluorescence spectrometer comprising a manual turret-mounted specimen distributor;

FIG. 2 shows a specimen distributor according to the invention for an automatic X-ray fluorescence spectrometer, and

FIG. 3 is a section on the line III-III of FIG. 2.

In the known dispenser shown in FIGURE 1, specimens 1 which it is required to analyse are placed on a manually controlled turret mechanism rotatably mounted on a spindle 2, the specimens 1 being brought seriatim to a position for analysis in front of an X-ray source 3 adapted to irradiate the specimen surface. Secondary radiation 4 from the specimen surface goes through a lattice 5 formed by thin parallel slats or strips or the like and passes to a receiver (not shown).

The automatic dispenser shown in FIG. 2 comprises a horizontal support member 6 defining a reference plane 7 in which surface 8 of a specimen 9 being analysed 3,415,987 Patented Dec. 10, 1968 (FIG. 3) must be disposed. At its centre the member 6 is formed with a passage 10 in which a spindle 11 is rotatably mounted perpendicularly to the reference plane 7; the spindle 11 has a transfer element in the form of a finger .12 adapted to move in a plane parallel to the reference plane 7. Some form of motor (not shown) drives the spindle or shaft 11. At the end remote from where it is secured to the spindle 11, the finger 12 is formed with a semicircular recess 13 whose diameter is equal to the diameter of the specimen holders 9. A specimen holder 9a engages in the recess 13 as the finger 12 passes by a specimen holder magazine, the latter taking the form of a tube 14 which has its axis perpendicular to the reference plane 7 and whose bottom end 15 terminates above the reference plane 7 by an amount greater than the thickness of a specimen holder 9. The specimen holders 9 are stacked inside the tube 14 and thus form a stock of specimens for analysis.

The support member 6 has an analysis window 16 and is formed with a recess 17 for removal of the specimen holders; the window 16 and recess 17 are pierced in the member 6 perpendicularly to the reference plane 7 and so distributed over the periphery of the support member as to be disposed on the path along which the recess 13 in the finger 12 travels. The window 16 should have a ring of at least three rollers; in the particular example shown the window 16 has a ring of four rollers 18a, 18b, 18c, 18d (FIGS. 2 and 3) against which the specimen holder bears by its surface 8. The rollers are freely rotatable on horizontal spindles 19a, 19b, 19c, 19d rigidly connected in the vertical wall of the Window 16 so that the surface 8 coincides with the reference plane 7. If required, the disc could be borne by its periphery on the edges of the support member 6, in which case such edges would be prolonged a short distance towards the inside of the window 16.

The specimen holder 9 disposed on the window 16 is horizontally guided by rollers 20a, 20b, 20c mounted on vertical spindles, the finger 12 being in a fixed position near the window 16 during the analysis operation. The rollers 20a, 20b are rigidly secured to the finger 12 near the recess 13 so as to cooperate with the roller 20c disposed outside the support member 6 and to contact the vertical wall 21 of the specimen holder 9. The rollers 20a, 20b are freely rotatable on their spindles, but the roller 200 is rotated via its spindle 22 by a motor (not shown) and has an edging inter alia of rubber which is in contact with the specimen holder wall 21 to rotate the same by friction.

Rollers 23a, 23]; disposed on the top of the holder 9 are freely rotatable on a horizontal spindle 24 secured to a sliding rod 25 biased by a helical spring 26 having one end abutting a shoulder 27 on the rod 25 and the other end abutting a stationary part such as a vacuum sealed casing 28 for the apparatus. The rollers 23a, 23b run on top surface 29 of the holder 9 and are maintained in bearing engagement therewith by the spring 26.

The entire dispenser as shown in FIG. 2 may be disposed in the vacuum sealed casing 28. This casing may be sealingly mounted on the top of a separate spectrometer means.

By disposing the entire dispensing device within the sealed casing and subjecting the entire enclosed area to a vacuum, a spectrometer having relatively weak beams such as 31 is able to analyse thoroughly a specimen through a recess 30 formed in the member 6 and through the open window 16.

The device according to the invention operates as follows:

During one cycle of operation the finger 12 makes one complete revolution during which it thrusts the previously analysed specimen 9 out of the window 16 and moves such specimen in the direction indicated by the arrow F1 to the recess through which the analysed specimen 9 drops to a recovery magazine (not shown) below the recess 17. As it continues its movement the finger 12 engages with the specimen holder 9a, removes the same from the magazine tube 14 and carries it along in the direction indicated by an arrow F2 as far as the analysis window 16. The finger 12 stops for the time required to analyse the specimen, then repeats the cycle as just described.

When the specimen holder is placed on the window 16, it is positioned vertically by the bottom rollers 18a, 18b, 18c, 18d and horizontally by the rollers 20a, 20b, 20c, 20d. Once the holder 9 has been accurately and completely reproducibly located in this way relatively to the spectrometer, the roller 20c rotates the holder 9 around its spindle to analyse the entire surface 8 of the specimen.

The distributor device is controlled either by the endof-travel contacts of the spectrogoniometer, for scanning analyses, or by a pulse delivered at the end of work of the counter, for fixed-angle working, or by an automatic clock pulse.

I claim:

1. X-ray fluorescence spectrometer apparatus for automatically positioning a plurality of specimens for analysis and characterized in that a horizontal support plate defining a reference plane corresponding to the surface of a specimen to be analysed has formed therein an opening through which a specimen may be analysed; cylindrical specimen holder means for each specimen; means for rotatably positioning and maintaining a single specimen holder over said opening during an analysis of the specimen contained by the holder; said plate further having a second opening formed therein through which the specimen holder may be removed from the plate; a holder magazine; a rotary transfer element, having its axis of rotation at the center of the support plate, for automatically transferring, one at a time, a plurality of specimen holders from the holder magazine to the analysis opening and then to the second opening, which holder magazine, opening and second opening are all disposed on the path of that part of the rotary element which receives a specimen holder.

2. Automatic distributor as set forth in claim 1, wherein the transfer element takes the form of a rotating finger formed, at the end remote from the axis of rotation, with a semicircular recess engageable by the specimen holders.

3. Automatic distributor as set forth in claim 1, wherein the means for horizontally positioning the specimen holders take the form of at least three vertical-spindle rollers which are in contact with the vertical edges of the specimen holders, at least two rollers being secured to the transfer element and the third roller being disposed outside the support plate and being rotated by a motor.

4. Automatic distributor as set forth in claim 1, wherein the elements for vertically positioning the specimen holders take the form of a ring of at least three horizontal-spindle rollers secured inside the analysis Window, such ring being disposed below the specimen holder and forming a support plane coincident with the reference plane.

5. Automatic distributor as set forth in claim 1, wherein elements disposed above the specimen holder for maintaining the same take the form of at least two rollers having horizontal spindles borne by a sliding support rod and are urged by resilient means into bearing engagement with the top surface of the specimen holder.

6. Automatic distributor as set forth in claim .1, wherein the specimen holder magazine takes the form of a tube whose axis is perpendicular to the reference plane and whose bottom edge is remote therefrom by an amount greater than the thickness of one specimen holder.

References Cited UNITED STATES PATENTS 3,047,124 7/1962 WeXlcr 88-14 3,263,078 7/1966 Thackara et al. 250-515 3,342,992 9/1967 Schmidt et al. 250--49.5

RALPH G. NILSON, Primary Examiner.

A. L. BIRCH, Assistant Examiner.

US. Cl. X.R. 250-495 

